Intake silencer for an internal combustion engine

ABSTRACT

An intake silencer for an internal combustion engine includes two casings mounted one on a carburetor and the other on the chassis of a vehicle, each acting as an expansion chamber, one or more connecting means for connecting both the casings, and pipe assemblies mounted on the casing which is mounted on the chassis for sucking air therethrough whereby a suction noise produced by the carburetor and the engine is markedly muffled.

United States Patent [19] Kawasaki m1 3,310,52 May 14, 1974 [54] INTAKE SILENCER FOR AN INTERNAL COMBUSTION ENGINE [75] Inventor: Masaru Kawasaki, Hamakita, Japan 73 Assignee: "Yamaha llatsudoki Kabushiki Kaisha, lwata-shi, Japan 22 Filed: Apr. 26, 1973 21 App]. No.: 354,763

[52] U.S. C1. 181/35 A, 181/35 R, 181/40,

' 181/47 R, 123/198 E [51] Int. Cl. F0ln l/02, FOln 1/06 [58] Field of Search 181/35 A; 123/198 E [56] References Cited UNITED STATES PATENTS 9/1954 Weldy l/I955 Sebok ..I8l/35A FOREIGN PATENTS OR APPLICATIONS 1,135,241 8/1962 Germany 123/198 E Primary Examiner-Richard B. Wilkinson Assistant Examiner-Vit W. Miska Attorney, Agent, or Firm-Flynn & Frishauf [5 7] ABSTRACT An intake silencer for an internal combustion engine includes two casings mounted one on a carburetor and the other on the chassis of a vehicle, each acting as an expansion chamber, one or more connecting means for connecting both the casings, and pipe assemblies mounted on the casing which is mounted on the chassis for sucking air therethrough whereby a suction noise produced by the carburetor and the engine is markedly muffled.

10 Claims, 2 Drawing Figures PATENTEDIIIAY \4 I974 3 Q 8 l O 5 26 SHEET 2 of 2 FIG. 2

BACKGROUND OF THE INVENTION This invention relates to an intake silencer for an internal combustion engine having no cleaner, adapted to be mounted on a vehicle such as a snowmobile and a cultivator.

A small-sized snowmobile, cultivator etc. usually run on a less dusty ground without necessity of mounting an air cleaner on the carburetor. However, pulsating sound wave is produced due to the sucked air into the carburetor and the engine, making a low-pitched loud noise like that of a pipe. Conventionally to avoid'this drawback, an expansion chamber has been provided, through which outer air is sucked and conducted to the carburetor and the engine. To muffle said suction noise without decreasing the power of the engine, it is effective to provide an expansion chamber having a large capacity and thereby to reduce a flow resistance for the sucker air. But the mounting of such large expansion chamber on the carburetor is disadvantageous to take up a large space around the engine, and furthermore to apply a great load to the mounting means of the carburetor on the engine.

An object of this invention is to provide an intake silencer for an internal combustion engine, capable of effectively muffling the suction noise produced by the sucked air into the carburetor and the engine without taking up a large space around the engine, and preventing a great load from being applied to a mounting means of the carburetor.

SUMMARY OF THE INVENTION To realize this object, the intake silencer of this invention has pipe assemblies mounted on acasing forming an expansion chamber. The pipe assemblies comprise a base wall of resilient material and a plurality of air inlet pipes of the same material formed integral with the base wall. The outer air is sucked into the casing through these pipe assemblies. Further, the intake silencer of this invention has first and second casings, wherein the former is mounted on the chassis and the latter on the carburetor, and each has a chamber acting as an expansion chamber in a sucked air passage for connecting the suction inlet of the carburetor to the outside, and one or more connecting means which link the first casing with the second one. The outer air is sucked through pipe-assemblies mounted on the first ,casing into the first casing and introduced through said 'connecting means and the second expansion chamber to the suction inlet of the carburetor.

With the intake silencer having such a construction, since the pipe assemblies are made of resilient material, the energy of the suction noise is decreased markedly, and; if the second casing is made smaller in size and the first casing is made larger in size, in a manner that the total capacity afforded by both casings is formed as great as the situation permits, then no excess load is applied to the mounting means of the carburetor on the engine, since only the smaller casing is mounted to the carburetor. As a result, possible damage at the mounting means due to the vibrations applied to the carburetor are prevented.

In this intake silencer, as the air system can be constructed with ample passages having a small flow resistance, the drop inv power of the engine becomes very small. Moreover, noise muffiing ability can be further improved, by selecting proper pipe assemblies having suitable number, length and position of the air inlet pipes and by making the said pipe-assemblies and the connecting means of elastic materials as rubber.

Furthermore, use of the elastic connecting means permits one casing to be easily connected to the other, and prevents possible damage caused at the connecting means due to the vibrations applied to the casings.

BRIEF DESCRIPTION OF THE DRAWING FIG. 2 is a front view, partly broken away, showing the embodiment of FIG. I.

DETAILED DESCRIPTION OF THE INVENTION Referring to FIGS. 1 and 2, an internal combustion engine 2 with a carburetor 3 is mounted on a chassis 1 of a vehicle. On the air inlet of the carburetor 3 is mounted a bell-shaped suction guide tube 4. A smaller casing 6 which forms a main part of the outer shell of an expansion chamber 5 of a smaller capacity, is directly attached to the carburetor 3 and the expansion chamber 5 communicates with the guide tube 4.

The casing 6 is blow-molded from synthetic resin having a flange 6a adjacent to its open end. The flange 6a is fixed to a mounting plate 8 by bolts 9, while the mounting plate 8 is fixed to the carburetor 3 by bolts 7, and thus the casing 6 is mounted on the carburetor 3 by bolts 7 and 9. Then the suction inlet 4 is enclosed by the casing 6. The casing 6 is provided with downwardly directed cylindrical projections 11 at the lower side thereof, each having an inlet opening 10. A large casing 13 which forms the outer shell of an expansion chamber 12 of larger capacity, is mounted on the chassis 1 below the casing 6. The casing 13 is blow-molded from synthetic resin and has at its top surface cylindrical projections 15, each having an outlet opening 14.

Between the both casings 6 and 13, connecting means or ducts 16 are provided, which are formed in the shape of bellows and made of elastic material such as rubber.

The upper and lower open ends of each duct 16 are fitted to the downwardly open projection 11 of the casing 6 and the cylindrical projection 15 of the casing 13 respectively, linking the smaller expansion chamber 5 with the larger one 12. On the both opposite side walls of the casing 13 are provided respective circular openings 17, into which are fitted pipe-assemblies 24 to suck the outer air. Each pipe-assembly 24' is constituted by a circular base wall 18 having an annular groove 19 at its periphery, and a plurality of interiorly extending inlet pipes 20 formed integral with the base wall 18. Each inlet pipe 20 has an air suction hole 21, so that the expansion chamber 12 opens to the outer air through the open ends 20a, and 20b, of the inlet pipe 20. The pipe-assembly 24 is made of rubber-like material and resiliently and detachably fitted into the opening 17 with its annular groove 19 touching the base wall 18. The respective open ends 20a of the opposite pipeassemblies 24 are positioned opposite to each other.

The reference number 22 indicates mounting means or an intake manifold, which permits the engine 2 to communicate with the carburetor 3, and 23 indicates '3 an engine cover in which the front portion of the engine 2 is located.

When the engine 2 is driven, the outer air is sucked, as shown by arrows in FIGS. 1 and 2, through air suction hole 21 into the expansion chamber 12, and then led through the ducts 16, the expansion chamber and suction guide tube 4 into the carburetor 3 and the engine 2. Suction noise produced by the carburetor 3 and the engine 2 is mufiled through the expansion chamber 5, the ducts 16, the expansion chamber 12 and air suction holes 21 and emitted to the outside.

According to the intake silencer of this invention, since the ducts l6 and the pipe assemblies 24 are both made of resilient material, and thus an excellent noise muffling effect can be obtained. Particularly, the air inlet pipes very effectively reduce the suction noise since they, made of resilient material and having broad inner surfaces in comparison with their volumes, allow the noise to diffuse through them. Moreover, the noise muffling ability can be further improved, by selecting proper pipe assemblies having suitable number, length and position of the air inlet pipes. Since only the casing 6 is mounted to the carburetor 3 and the casing 13 is equipped to the chassis l, a greater total capacity afforded by both casings 6 and 13 can be utilized than a capacity offered by a single casing mounted on the carburetor 3. Consequently .the suction noise produced from the carburetor 3 and the engine 2 is markedly muffled, then emitted to the outside in a very low level. As described above, the casings 6 and 1 3 put together offer a great total capacity,- permitting many parts of the air suction system to be formed greater in size, thus and smaller in air. flow resistance, then the drop in power of the engine 2 can be very small.

Since only the smaller casing 6 is mounted to the carburetor 3, no overload is applied to the mounting means 22, damages are scarcely occurred at this portion. The connection between the casings 6 and 13 can easily be executed by the elbow-like resilient ducts 16, even if the casings 6 and 13 are somewhat displaced from each other. Furthermore, because of the said resilient property of the ducts 16, damage of the casings 6 and 13 and the ducts l6 rarely occur, even if mutual vibrations take place between the casings 6 and 13.

What is claimed is:

1. An intake silencer for an internalcombustion engine having a carburetor comprising:

a casing (13) having side walls and communicating with the air inlet of the carburetor of the engine, said casing (13) forming an expansion chamber (12) and having at least one opening (17) in one of the side walls thereof; and

at least one pipe-assembly (24) which comprises a base wall (18) of resilient material having an annular groove (19) in the periphery thereof and a .plurality of air inlet pipes (20) of the same resilient material formed integral with the base wall (18), said at least one pipe assembly (24) being adapted to bedetachably fitted into the at least one opening 17) of said side wall with the annular groove (19) contacting said side wall.

2. An intake silencer as claimed in claim 1 wherein said casing (13) has a pair of openings (17) in respec- 4 tive side walls, said openings (17 being opposite to each other, and comprising a pair of pipe assemblies (24) detachably fitted each into respective openings (17).

3. An intake silencer as claimed in claim 1 wherein the airinlet pipes (20) of said at least one pipe assembly (24) extend within said casing (13).

4. An intake silencer for an internal combustion engine of a vehicle comprising:

a first casing (13) having side walls and forming a first expansion chamber (12). mounted on the chassis.(l) of the vehicle and having at least one opening (17) in one of its side walls;

at least one pipe assembly (24) which comprises a base wall (18) of resilient material having an an nular groove (19) in the periphery thereof and a plurality of air inlet pipes (20) of the same resilient material formed integral with the base wall (18), said at least one pipe assembly (24) being adapted to be detachably fitted into the at least one opening 17) of said side wall with the annular groove (19) contacting said side wall;

a second casing (6) forming a second expansion chamber (5) and mounted on the carburetor of the engine to communicate with the air inlet of the carburetor; and

at least one duct (16) for linking said first and second casings.

5. An intake silencer as claimed in claim 4 wherein said first casing (13) has a pair of openings (17) in respective side walls of said first casing, said openings (17) being opposite to each other, and comprising a pair of pipe assemblies (24) detachably fitted each into respective openings (17).

6. An intake silencer as claimed in claim 4 wherein the air inlet pipes (20) of said at least one pipe assembly (24) extend within said first casing (13).

7. An intake silencer as claimed in claim 4 wherein said first casing (13) is larger than said second casing (6).

8. An intake silencer as claimed in claim 4 wherein said duct (16) is made of resilient material.

9. An intake silencer as claimed in claim 4 comprising a pair of ducts (l6) linking said first and second casings, the ends of said ducts being connected to said second casing (6) such that their axes extend substantially parallel with the air outlet of the carburetor located between them.

10. An intake silencer as claimed in claim 4 wherein: said first casing (13) has a pair of openings (17) in respective side walls of said first casing (13). said openings (17) being opposite to each other; a pair of pipe assemblies (24) are detachably fitted each into respective openings (17), said air inlet pipes (20) of both of said pipe assemblies 24) extending within the first casing (13); said first casing (13) is larger than said second casing (6); a pair of ducts (16) made of resilient material are provided and link said first and second casings, the ends of said ducts being connected to said second casing (6) such that their axes extend substantially parallel with the air outlet of the carburetor located between them. 

1. An intake silencer for an internal combustion engine having a carburetor comprising: a casing (13) having side walls and communicating with the air inlet of the carburetor of the engine, said casing (13) forming an expansion chamber (12) and having at least one opening (17) in one of the side walls thereof; and at least one pipe-assembly (24) which comprises a base wall (18) of resilient material having an annular groove (19) in the periphery thereof and a plurality of air inlet pipes (20) of the same resilient material formed integral with the base wall (18), said at least one pipe assembly (24) being adapted to be detachably fitted into the at least one opening (17) of said side wall with the annular groove (19) contacting said side wall.
 2. An intake silencer as claimed in claim 1 wherein said casing (13) has a pair of openings (17) in respective side walls, said openings (17) being opposite to each other, and comprising a pair of pipe assemblies (24) detachably fitted each into respective openings (17).
 3. An intake silencer as claimed in claim 1 wherein the air inlet pipes (20) of said at least one pipe assembly (24) extend within said casing (13).
 4. An intake silencer for an internal combustion engine of a vehicle comprising: a first casing (13) having side walls and forming a first expansion chamber (12), mounted on the chassis (1) of the vehicle and having at least one opening (17) in one of its side walls; at least one pipe assembly (24) which comprises a base wall (18) of resilient material having an annular groove (19) in the periphery thereof and a plurality of air inlet pipes (20) of the same resilient material formed integral with the base wall (18), said at least one pipe assembly (24) being adapted to be detachably fitted into the at least one opening (17) of said side wall with the annular groove (19) contacting said side wall; a second casing (6) forming a second expansion chamber (5) and mounted on the carburetor of the engine to communicate with the air inlet of the carburetor; and at least one duct (16) for linking said first and second casings.
 5. An intake silencer as claimed in cLaim 4 wherein said first casing (13) has a pair of openings (17) in respective side walls of said first casing, said openings (17) being opposite to each other, and comprising a pair of pipe assemblies (24) detachably fitted each into respective openings (17).
 6. An intake silencer as claimed in claim 4 wherein the air inlet pipes (20) of said at least one pipe assembly (24) extend within said first casing (13).
 7. An intake silencer as claimed in claim 4 wherein said first casing (13) is larger than said second casing (6).
 8. An intake silencer as claimed in claim 4 wherein said duct (16) is made of resilient material.
 9. An intake silencer as claimed in claim 4 comprising a pair of ducts (16) linking said first and second casings, the ends of said ducts being connected to said second casing (6) such that their axes extend substantially parallel with the air outlet of the carburetor located between them.
 10. An intake silencer as claimed in claim 4 wherein: said first casing (13) has a pair of openings (17) in respective side walls of said first casing (13). said openings (17) being opposite to each other; a pair of pipe assemblies (24) are detachably fitted each into respective openings (17), said air inlet pipes (20) of both of said pipe assemblies (24) extending within the first casing (13); said first casing (13) is larger than said second casing (6); a pair of ducts (16) made of resilient material are provided and link said first and second casings, the ends of said ducts being connected to said second casing (6) such that their axes extend substantially parallel with the air outlet of the carburetor located between them. 